Fatty acid composition in fertilized eggs of cod (Gadus morhua) originating from the Baltic Sea and the Skagerrak respectively
Pickova, J.; Dutta, P. (1995). Fatty acid composition in fertilized eggs of cod (Gadus morhua) originating from the Baltic Sea and the Skagerrak respectively, in: Lavens, P. et al. (Ed.) Larvi '95: Fish & Shellfish Symposium, Gent, Belgium, September 3-7, 1995. EAS Special Publication, 24: pp. 34
In: Lavens, P.; Jaspers, E.; Roelants, I. (Ed.) (1995). Larvi '95: Fish & Shellfish Symposium, Gent, Belgium, September 3-7, 1995. Special Publication European Aquaculture Society, 24. European Aquaculture Society: Gent. ISBN 90-71625-14-1. XXVI, 521 pp., meer
In: Special Publication European Aquaculture Society. European Aquaculture Society: Bredene. ISSN 0774-0689, meer
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| Abstract |
Hatching and rearing experiments have been performed with cod from the Baltic Sea (a semi-enclosed brackish water sea) and an oceanic cod stock from the Skagerrak. Matching success was different, irrespective of salinities used, with rates <30% achieved with the Baltic cod eggs compared to >80% for the Skagerrak stock. Reproductive problems have been registered in the Baltic Sea, i.e. the so-called M74 on salmon, believed to be caused by environmental disorders. Indications on problems in cod are also registered. An investigation has started aiming at finding reasons for the poor hatching of Baltic cod. The first part was conducted in 1994 and confined to the egg stage. Four different groups of cod were sampled, one from a Skagerrak population, transferred to the rearing station 2 months before spawning, and three groups from the Baltic. These cods were trawled in ICES subdivision 25, 2 months, 7 months and 19 months before the start of the 1994 spawning season. All cods were fed sprat (fished in the Skagerrak) and dry pellets (FelleskjØpet) during the time spent at the station. The eggs were spawned spontaneously in tanks (9000 l) at the rearing station and collected with a plankton net. The eggs were incubated individually in tissue culture plates (96 cups in each) and were followed until and including hatching. The primary factors looked at were the early cleavage pattern of the fertilized eggs and the fatty acid composition in the eggs. Samples of newly fertilized eggs from a number of batches were preserved in -80°C and analysed in several respects. Results from the lipid analyses will be related to the hatching success. The early cell cleavage pattern showed the same tendency as the hatching rates, i.e. eggs of the Baltic cod stock had a significantly higher rate of asymmetry at the four and eight cell stage than eggs from the Skagerrak stock. |
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